JPH0129845B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method of operating a blast furnace for iron-making, in particular, a heat-resistant hot air control valve made of ceramics or the like is provided in a tuyere branch pipe, and a part of the blast furnace is operated by the hot air control valve. This invention relates to a method of operating a blast furnace that increases or decreases the air flow rate of the tuyere branch pipe and prevents the inside of the furnace from slipping in the direction of the tuyeres and from falling raw ore.

[Conventional technology]

Generally, a blast furnace for steelmaking has 30 to 40 tuyeres on the outer periphery of the lower part of the furnace for blowing high-temperature hot air into the furnace. 900~1300℃, humidity 7~50
Humidity-controlled hot air of about g/Nm ³ (maximum 60 g/Nm ³ ) is blown into the furnace. On the other hand, the raw material ore is charged to form a uniform layer through a charging bell, movable armor, etc., and reacts in the furnace with high-temperature hot air blown from the lower part of the furnace, reducing, softening, and partitioning. After melting and melting, it becomes hot metal in the furnace pool.1
Hot metal is tapped from the taphole 10 to 20 times per day.

In the operating method of such a blast furnace, problems such as poor uniformity of gas flow in the circumferential direction, non-uniform gas flow due to adhesion of fused materials to the inner wall of the furnace, or non-uniform charging of raw materials, etc. As shown in FIG. 1, the "one-sided" phenomenon of the raw material charge occurs.

Furthermore, as shown in FIG. 3, the non-uniformity of the gas flow in the circumferential direction causes a so-called "green ore fall" phenomenon in which there is a large amount of unreduced ore at the tip of the tuyere.

These "slip-over" phenomena cause the reactions in the blast furnaces to malfunction and eventually cause a wind outage, and the "green ore drop" phenomenon causes fluctuations in the Si content in the hot metal or a drop in the hot metal temperature at the taphole. There was a need for a solution in terms of production, hot metal composition, and temperature control.

On the other hand, conventionally, it has been difficult to control the amount of high-temperature hot air blown from each tuyere branch pipe due to the material of the control valve, and it has not been possible to control the amount of air blown from each tuyere. For this reason, the phenomenon of "green ore falling" often occurs at the tuyeres in the direction where the charge descending speed is high. This can be seen from the fact that the Si content in the pig iron or the temperature of the hot metal at the taphole exiting from the direction where the "green ore rain" phenomenon occurs is different from that of the hot metal coming from other tapholes.

In other words, the above-mentioned "one-sided" and "green ore falling" phenomena of the charge are caused by the non-uniformity of the gas, so in order to solve this, the air flow rate of the tuyere branch pipe in the circumferential direction is controlled. It was requested to do so.

Conventionally, attempts have been made to use control valves made of metal valve bodies as flow rate control valves for these tuyeres, but the valve body lacks heat resistance and cannot withstand high temperatures, so water-cooling the valve body has also been adopted. However, it was not possible to put it into practical use due to the large heat loss, and although water-cooled control valves or dampers were installed in the annular high-temperature hot air pipe to control the overall air flow, Controlling the amount of air blown from each tuyere had not yet been put into practical use.

As a hot air control valve for solving these above-mentioned problems, the applicant proposed a valve plate 21 of a valve body 13 and a valve shaft 2 as shown in FIG.
The patent application has been filed for a butterfly valve 8 in which the valve body is housed in a casing 31 which is lined with heat-resistant members 36 and 37 to form a flow path.

[Problem that the invention seeks to solve]

The present invention is a blast furnace operating method that prevents the "one-side" phenomenon of the charge and the "green ore falling" phenomenon to the tip of the tuyere, maintains proper and stable blast furnace operation, and improves the efficiency of this operation. An object of the present invention is to provide an operating method for constantizing the components of hot metal produced and the temperature of the hot metal.

[Means for solving problems]

The present invention has been made to solve the above-mentioned problems. In other words, the above-mentioned application 1983-
The heat-resistant hot air control valve made of ceramic proposed in No. 170080 and a further improved hot air control valve are installed in each tuyere branch pipe, and by controlling the air flow rate of each tuyere with the hot air control valve, the equipment inside the blast furnace can be improved. “One side” phenomenon of the container and “green ore falling” at the tip of the tuyere
This is a blast furnace operating method that prevents this phenomenon.

That is, the gist of the present invention is that when high-temperature hot air is blown into the furnace from the furnace tuyeres via the tuyere branch pipes, a hot air control valve is provided for each tuyere branch pipe, and the hot air control valve controls the blowing of some of the tuyeres. There is a method of operating a blast furnace that increases or decreases the amount of air blown from the branch pipe to prevent the inside of the furnace from slipping in the direction of the tuyeres and from falling raw ore.

However, the hot air control valve is a thermal control valve in which (i) the valve plate of the valve body and the valve stem are integrally constructed of ceramic, and (ii) the valve plate of the valve body and the valve stems provided above and below the valve plate. and a support shaft integrally constructed of ceramic, and have an inner diameter approximately equal to the flow path of high-temperature hot air.
a pair of annular support members made of ceramic formed to rotatably support the lower part of the valve body, and the support members are connected from both sides of the valve plate, the base of the valve shaft, and the support shaft. (iii) a cylindrical first heat-resistant member and a cylindrical second heat-resistant member that is longer than the first heat-resistant member and is fitted into the first heat-resistant member; Each of the first and second heat-resistant members is divided into two from the center, and these first and second heat-resistant members are inserted into both sides of a valve body disposed at the center of the casing to rotatably support the valve body, and the first and second heat-resistant members are A hot air control valve in which presser members are fitted on both sides of the casing, fasteners are attached to the outer periphery of the casing, and the fasteners are welded to the inner wall of the casing to connect them together, (iv) (ii) above. In the hot air control valve of (iii) above, the chamber formed between the valve shaft of the valve body and the flange of the casing is connected to the drain discharge portion through a passage provided in the flange.

These things achieve the object of the present invention. [Function] The amount of air blown from the branch pipe of the tuyere, which has been difficult to control in the past and which has a lot of "overflow" and "green ore fall", can be controlled by the hot air control valve configured from (i) to (iv) above. By lowering the amount of combustion air in the direction of the tuyere, the rate of melting and reduction reactions in this area is reduced.

As a result, the charge descending speed is lower than in other directions, and the one-side slippage recovers.

In addition, as shown in Figure 3, by reducing the amount of air blown from the branch pipes of tuyeres No. 6a ₆ to 6a ₈ , which correspond to "raw ore falling," it is possible to take sufficient time to melt the iron ore, so that "raw ore is falling.""Orerain" will be reduced.

As a result of the above two actions, the charge level is made uniform in the circumferential direction, and it is also possible to prevent the phenomenon of local "green ore falling" at the tuyere and to recover from the unevenness, which was previously considered difficult. Appropriate blast furnace operation is maintained, which also brings about excellent effects such as making the temperature of the hot metal at each tap hole and the Si content in the hot metal constant.

As for the hot air control valve used in the blast furnace operating method of the present invention, the hot air control valve shown in FIGS. 4 to 6 in the embodiment described later has a strong valve body, a wide flow rate control range, and is easy to manufacture. This is suitable because it is easy to clean and has a drain removal mechanism.

Examples of embodiments of the present invention will be described below. [Example] Figure 1 is an explanatory diagram of an example of the present invention,
The figure is a diagram showing the arrangement of the taphole of the blast furnace, FIG. 3 is an explanatory diagram showing the arrangement of the tuyere, and FIG. 4 is an explanatory diagram showing the installation of the hot air control valve.

In the figure, 1 is a blast furnace, 2 is a furnace wall, 3 is a charging bell, 4 is an ore and coke layer, 4a is an ore layer, 5 is an ore layer level sensor, 6 is a tuyere, 7 is a blowing tuyere branch pipe, 8 is a hot air control valve, 9 is an annular hot air pipe,
10 is a taphole, 11 is a sump section, 12 is a calculation control device, and 18 is a raw ore drop-off section.

900 to 1300 to react the ore and coke layer 4 charged into the blast furnace 1 through the charging bell 3.
℃ and absolute humidity of 7 to 50 g/Nm ³ is blown from the annular hot air pipe 9 through the blowing branch pipe 7 and from the tuyere 6 . The slag and pig iron reacted and generated in the furnace form a slag layer and a pig iron layer in the sump 11 in the lower part of the furnace, and are periodically passed through the tap hole 10 to the tap hole (not shown) to the large trough. It is discharged.

In this embodiment, the tap holes (inner diameter 50 mmφ) are 10a, 10b, 10c, 10 as shown in FIG.
d, each taphole has its own blowing tuyere (tuyere diameter
A total of 4 blocks of 10 pipes (100 to 140 mmφ) are arranged in one block, and a total of 40 tuyeres are arranged, and a hot air control valve 8 is provided for each tuyere branch pipe.

First, in order to prevent the furnace from slipping, which is the object of the present invention, the level of the ore and coke layer 4 in the furnace in the circumferential direction is measured in advance by the ore layer level sensor 5.
This is measured by the system and compared with the appropriate level of the computer control device through sounding to monitor the single side situation inside the furnace. If, as shown in FIG. 1, the mineral layer level of 4a is lower than the standard 4b and one side is falling, the tuyere block corresponding to 4a, for example, each of the tuyere branch pipes 7a ₆ to 7a ₈ of 9a. By controlling the hot air control valves 8a ₆ to 8a ₈ provided in each furnace and reducing the amount of air blown, the amount of combustion oxygen supplied is reduced, and the melting and reduction reaction rates in the corresponding portions of the furnace are reduced. As a result, the charge descending speed decreases in other directions, for example, 4b, and the one side recovers, and 4a, 4
The level of b is equalized.

On the other hand, the phenomenon of "green ore falling" often occurs in conjunction with the above-mentioned one-sided phenomenon in the furnace. Sufficient time is allowed to melt the stone, and the phenomenon of "raw ore falling" is eliminated.

Furthermore, the phenomenon of “raw ore falling” occurs at tap ports 10a to 10.
Abnormalities in hot metal temperature and hot metal components such as Si from each taphole d are detected by the calculation control device 12, and thereby the tuyeres 6a ₁ to 6a ₁₀ corresponding to the corresponding taphole, for example 10a, are detected. Among them, tuyeres 6a ₆ to 6a ₈
The existence of a "live ore fall" zone 18 at the tip of the ore level sensor 5 is detected by visual observation from a raw ore fall detection sensor (tuyere luminance meter) or a tuyere viewing window. After confirming this, control the hot air control valves 8a ₆ - 8a ₈ of the corresponding tuyere branch pipes 7a ₆ - 7a ₈ , reduce the air flow rate of the tuyeres 6a ₆ - 6a ₈ , and adjust the melting and reduction times as described above. By doing so, the charging level 4 is made uniform in the circumferential direction, and the tuyeres 6a ₆ to 6a ₈
It also eliminates the localized ``live ore fall'' at the tuyere.

In this case, the abnormality may be notified to the operator by an alarm device (not shown), and the corresponding hot air control valve may be controlled manually or automatically by the calculation control device 12.

By performing such operations, it was possible to recover "one edge" and prevent "green ore falling", which had been considered difficult in the past, and proper blast furnace operation was maintained.

Furthermore, due to the reduction in "sloping" and "green ore falling" of the charge, the non-uniformity of the cohesive zone in the circumferential direction at the bottom of the blast furnace is reduced, and the molten iron composition, molten iron temperature,
Variation in slag components, i.e. tap-to-tap Siσ _si = 0.1
% to 0.08%.

In addition, "raw ore falling" to the tip of the tuyere in the direction where "one side" had conventionally occurred is more common than other tuyeres, and ore falls from the copper water-cooled small tuyere (protruding 30 to 40 cm into the furnace). Although wear and tear caused by impact were severe, by implementing the operating method of the present invention, the tuyere replacement cycle was extended from 3 months to 6 months.

Next, a hot air control valve for carrying out the method of the present invention will be described. In the present invention, the eighth
The butterfly valve shown in the figure has great heat resistance.
This valve can be put to practical use as a hot air regulating valve 8 in the tuyere branch pipe 7.

However, the present applicant has further developed a hot air control valve in which the strength of the valve plate for opening and closing the flow path of the butterfly valve and the flow rate control range are significantly increased.

FIGS. 5 and 6 are front and side views showing a portion of the improved hot air control valve in cross section. Fifth
In the figure and FIG. 6, 8 is a hot air control valve, 13 is a valve body, 14 is a casing that accommodates the valve body, 15 is a drive section for the valve body 13, and 16 is a drain discharge section provided in the drive section 15.

In the valve body 13, 21 is a disc-shaped valve plate, 22
23 is the valve shaft provided on the upper part of the valve plate 21, and 23 is the valve plate 21.
A support shaft provided at the bottom of the valve shaft 22 on the same line as the valve shaft 22,
These are integrally constructed of ceramics.

In the casing 14, 31 is a steel outer cylinder having flanges 32, 32a and 33 at both ends and the upper part, and the flange 33 has a passage opening into the chamber A formed between the flange 33 and the valve shaft 22. 3
4 is provided.

Reference numerals 35 and 35a are support members made of ceramics that support the valve plate 21 from both sides of the valve plate 21 via bushes, and 36 and 36a are support members whose outer diameter is equal to that of the outer cylinder 31.
3 with a cylindrical first heat-resistant member that matches the inner diameter of
7, 37a is a cylindrical second heat resistant member whose outer diameter matches the inner diameter of the first heat resistant member 36, 36a and is longer than the first heat resistant member 36, 36a; 38 is a hot air flow path;
39, 39a are cutout portions provided on the inner periphery of the opposing portion;
40, 40a are semicircular cutout portions 40, 40a provided above the cutout portions 39, 39a, through which the valve shaft 22 is inserted;
1, 41a is the first heat-resistant member 3 at the outer periphery of the end portion.
6, 36a are stepped portions cut out to the ends. 4
2, 42a is a ring-shaped support member made of ceramics, the outer diameter of which is the same as the second heat-resistant member 37, 37a.
The inner diameter is formed to match the inner diameter of the second heat-resistant members 37, 37a, and hence the diameter of the flow path 38. 43 and 43a are bushes. 44, 44a are ring-shaped holding members made of heat-resistant material, the outer diameter of which matches the inner diameter of the outer cylinder 31, the inner diameter of which matches the stepped portions 41, 41a of the second heat-resistant members 37, 37a, and the ends thereof L-shaped cutout portions 45, 45a are formed. 47,47
a is a ring-shaped steel stopper, which is attached to the holding members 44, 44a via the gland packings 48, 48a.
It is attached to the cutout part of the outer cylinder 31 and welded to the inner wall of the outer cylinder 31 to fix each of the above-mentioned parts integrally within the outer cylinder 31.

In the drive unit 15, 51 is a motor, 52 is a cover that covers the connecting part between the output shaft of the motor 51 and the valve shaft 22, and a flange 53 is provided at the lower part, and the flange of the casing 14 is attached to the flange 53. A hole 54 is provided which communicates with the passage 34 provided in the hole 33 .

In the drain discharge section 16, 61 is a drain pipe whose one end is fixed to the flange 53 of the cover 52 and communicates with the hole 54, 62 is a valve provided on this pipe 54, and 63 is a stem supporting the pipe 61.

In the hot air control valve configured as described above, the control valve 8 is connected to the blowing passage of the blowing branch pipe 7 of the tuyere 6 by the flanges 32 and 32a, and the valve shaft 22 is rotated by the motor 51 of the drive section 15. For example, the valve plate 21 rotates within the flow path 38 about the valve shaft 22 and the support shaft 23, and can adjust the flow rate of hot air flowing through the flow path 38 over a wide range.

According to the example, when the diameter of the fluid flow path (that is, the inner diameter of the support member) is 200 mm and the outer diameter of the valve plate is 198 mm (therefore, the gap is 1 mm), the flow rate when the valve plate is fully open is Q, and when the valve plate is fully closed, If the flow rate at time is Q ₁ , the ratio between the two is Q ₁ /Q
The flow rate ranged from about 5% to 100% as shown in I in Figure 7, making it possible to adjust the flow rate over a very wide range. In addition, in Figure 7, Q ₁ /Q is when the above gap is 5.2 mm, and Q 1 /Q is when the gap is 15 mm.
It shows Q ₁ /Q, and it shows a great effect on controlling the amount of air blown from the tuyere from the tuyere branch pipe mentioned above.

In addition, as mentioned above, this hot air control valve has a symmetrical structure in which the first and second heat-resistant members are divided into two from the center, and are inserted on both sides of the valve body disposed at the center of the outer cylinder to rotate the valve body. A holding member of a symmetrical structure is fitted to the outer periphery of both heat-resistant members, and a stopper is attached to the outer periphery of the holding member and welded to the inner wall of the outer cylinder to connect and fix them together. Not only is it easy to manufacture, but also the flow path can be formed accurately.
Therefore, the gap between the valve plate and the inner wall of the flow path can be made as small as possible, and the range of adjustment of the flow rate of hot air can also be expanded.

Furthermore, the hot air control valve is provided with a drain discharge part 16,
Since hot air or condensate that enters the chamber formed between the flange of the casing and the valve stem is discharged in a timely manner, the hot air may solidify in the chamber and interfere with the rotation of the valve stem, or prevent rust, etc. This prevents the deterioration of the material without causing any risk of damage.

When the hot air control valve configured as described above is applied to the blast furnace operating method of the present invention, the object can be achieved.

〔Effect of the invention〕

According to the operating method of the blast furnace of the present invention, “one side in the furnace”
The phenomenon of "raw ore falling" can be prevented by controlling the hot air control valve installed in the relevant blower branch pipe and reducing the amount of air blown from the corresponding tuyere, thereby slowing down the melting and reduction reactions in the furnace. This makes it possible to uniformize the charging level and to recover localized raw ore from the tuyere and recovery of one side, which was previously difficult.

This has the excellent effect of uniformizing the melting temperature in the circumferential direction of the furnace, that is, for each tap hole, and the hot metal components such as Si, and maintaining proper blast furnace operation.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of an embodiment of the present invention, and FIG.
Figure 3 is an explanatory diagram showing the arrangement of the taphole of a blast furnace, Figure 3 is an explanatory diagram showing the tuyere arrangement, Figure 4 is an explanatory diagram of the installation of the hot air control valve, and Figures 5 and 6 are the hot air control used in the present invention. A front view and a side view showing a partial cross section of the valve, Fig. 7 is a graph showing the relationship between the gap between the flow path and the valve plate and the flow rate, and Fig. 8 shows an example of a conventional butterfly valve for high temperature use. FIG. In the figure, 1: blast furnace, 4: ore and coke layer, 4a: Kataveri ore layer, 4b: normal ore layer,
6: Tuyere, 7: Blowing tuyere branch pipe, 8: Hot air control valve,
9: Annular pipe, 10: Tap hole, 12: Computation control device, 13: Valve body, 14: Casing, 15: Valve body drive section, 16: Drain discharge section, 18: Raw ore unloading section, 21: Valve Plate, 22: Valve shaft, 23: Support shaft, 3
1: Outer cylinder, 34: Passage, 35, 35a: Support member, 36, 36a: First heat resistant member, 37, 37
a: first heat resistant member, 38: channel, 42, 42a:
Ring-shaped support member, 43, 43a: Bush, 4
4, 44a: Ring-shaped holding member, 47, 47
a: Ring-shaped stopper, 61: Drain drain pipe,
62: Drain drain valve. In each figure, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] 1. When high-temperature hot air is blown into the furnace from the furnace tuyeres via the tuyere branch pipes, a hot air control valve is provided for each tuyere branch pipe, and the hot air control valve increases or decreases the air flow rate of some of the tuyere branch pipes. , a method of operating a blast furnace characterized by preventing internal slippage and falling of raw ore in the direction of the tuyere.